During the current grant period, a very sensitive fluorometric method for the separate quantitation of sphingosine, dihydrosphingosine and phytosphingosine has been developed. This technique will be applied for biological studies concerning the quantitative distribution of the different individual sphingolipids in various structures of the central and peripheral nervous system of representative vertebrates and invertebrates and in various tissues of a given species. Our immediate goals are comparative studies concerning the quantitative distribution of dihydrosphingosine and sphingosine in the cerebroside and sphingomyelin fractions of the evolutionary series of vertebrates. The approach to this project is anticipated to be rather expedient because relatively simple techniques for the separation of cerebrosides and sphingomyelin are available. They need only to be tested for their suitability for the fluorometric lipid base assay following the separation and methanolysis of the respective parent sphingolipids. The second project of our planned studies will be the use of the fluorometric lipid base assay for the quantitation of the individual gangliosides obtained by TLC of the upper phases of tissue lipid extracts obtained according to the procedure of J. Folch et al. The high sensitivity of our technique, and the fact that the fluorescent spots of the dansylated lipid bases are quantitated by fluorometric scanning on the plate without the dilution which would accompany their elution appears to render it particularly useful for studies in the field of comparative biochemistry.